This invention relates generally to atmospheric gas burners, particularly to gas burners for domestic cooking appliances. The invention more specifically relates to improving the operating range of gas burners.
Atmospheric gas burners are commonly used as surface units in household gas cooking appliances. These gas burners typically comprise a burner head having a number of ports formed therein. A mixer tube introduces a mixture of fuel and air into the burner head. The fuel-air mixture passes through the ports and is ignited and burned. Achieving adequate operating range or turndown is a critical design parameter for atmospheric gas burners. Turndown is particularly important for gas burners used in gas cooking appliances because such burners are often required to operate over a wide range of inputs.
Many current gas burners are unable to provide an adequate simmer operation. This is because turndown is limited by the minimum gas velocity at the burner ports that will support a stable flame. When fuel input is reduced for simmer operation, the gas velocity through the ports becomes lower. Eventually, the gas velocity can become so low as to result in no flame at all or a marginal flame that is prone to being extinguished by disturbances in the surroundings, such as room drafts or oven door slams. The problem is particularly evident in the so-called sealed gas burner arrangements, i.e., burner arrangements lacking an opening in the cooktop surface around the base of the burner to prevent spills from entering the area beneath the cooktop, thereby facilitating cleaning of the appliance.
Accordingly, there is a need for an atmospheric gas burner capable of achieving extended turndown while maintaining the look, feel and cleanability of conventional cooktop burners.